Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Net revenues:	$ 1,587.6	$ 1,305.0	$ 3,116.2	$ 2,655.7
Percent change in net revenues	21.70%		17.30%
Gross profit:	$ 1,034.1	843.7	$ 2,027.9	1,700.5
Percent change in gross profit	22.60%		19.30%
Operating profit	$ 472.6	383.9	$ 924.2	777.5
Percent change in operating profit	23.10%		18.90%
Long-lived assets:	$ 231.0	193.0	$ 231.0	193.0
Percent change in long-lived assets	19.70%
Corporate
Segment Reporting Information [Line Items]
Unallocated corporate general and administrative expenses	$ 54.6	50.3	105.7	94.7
Application Software
Segment Reporting Information [Line Items]
Net revenues:	$ 591.6	398.4	$ 1,168.2	803.5
Percent change in net revenues	48.50%		45.40%
Gross profit:	$ 409.3	273.8	$ 808.0	544.2
Percent change in gross profit	49.50%		48.50%
Operating profit	$ 154.2	113.4	$ 307.9	211.0
Percent change in operating profit	36.00%		45.90%
Long-lived assets:	$ 127.9	88.5	$ 127.9	88.5
Percent change in long-lived assets	44.50%
Network Software & Systems
Segment Reporting Information [Line Items]
Net revenues:	$ 458.7	422.0	$ 898.9	860.2
Percent change in net revenues	8.70%		4.50%
Gross profit:	$ 318.8	284.8	$ 618.2	578.0
Percent change in gross profit	11.90%		7.00%
Operating profit	$ 150.5	130.6	$ 286.0	269.3
Percent change in operating profit	15.20%		6.20%
Long-lived assets:	$ 52.7	46.5	$ 52.7	46.5
Percent change in long-lived assets	13.30%
Measurement & Analytical Solutions
Segment Reporting Information [Line Items]
Net revenues:	$ 397.0	363.9	$ 778.0	729.1
Percent change in net revenues	9.10%		6.70%
Gross profit:	$ 230.4	221.5	$ 455.1	436.1
Percent change in gross profit	4.00%		4.40%
Operating profit	$ 124.0	123.0	$ 248.1	237.0
Percent change in operating profit	0.80%		4.70%
Long-lived assets:	$ 34.3	37.4	$ 34.3	37.4
Percent change in long-lived assets	(8.30%)
Process Technologies
Segment Reporting Information [Line Items]
Net revenues:	$ 140.3	120.7	$ 271.1	262.9
Percent change in net revenues	16.20%		3.10%
Gross profit:	$ 75.6	63.6	$ 146.6	142.2
Percent change in gross profit	18.90%		3.10%
Operating profit	$ 43.9	16.9	$ 82.2	60.2
Percent change in operating profit	159.80%		36.50%
Long-lived assets:	$ 16.1	$ 20.6	$ 16.1	$ 20.6
Percent change in long-lived assets	(21.80%)